Date Published: June 04, 2018
Publisher: Oxford University Press
Author(s): Jamie Hartmann-Boyce, Filippo Bianchi, Carmen Piernas, Sarah Payne Riches, Kerstin Frie, Rebecca Nourse, Susan A Jebb.
Diet is an important determinant of health, and food purchasing is a key antecedent to consumption.
We set out to evaluate the effectiveness of grocery store interventions to change food purchasing, and to examine whether effectiveness varied based on intervention components, setting, or socioeconomic status.
We conducted a systematic review of randomized controlled trials (search performed June 2017). Studies must have: aimed to change food purchasing; been implemented in grocery stores (real or simulated); reported purchasing; and had a minimal control or compared interventions fulfilling our criteria. Searching, screening, bias assessment, and data extraction followed Cochrane methods. We grouped studies by intervention type (economic, environmental, swaps, and/or education), synthesized results narratively, and conducted an exploratory qualitative comparative analysis.
We included 35 studies representing 89 interventions, >20,000 participants, and >800 stores. Risk of bias was mixed. Economic interventions showed the most promise, with 8 of the 9 studies in real stores and all 6 in simulated environments detecting an effect on purchasing. Swap interventions appeared promising in the 2 studies based in real stores. Store environment interventions showed mixed effects. Education-only interventions appeared effective in simulated environments but not in real stores. Available data suggested that effects of economic interventions did not differ by socioeconomic status, whereas for other interventions impact was variable. In our qualitative comparative analysis, economic interventions (regardless of setting) and environmental and swap interventions in real stores were associated with statistically significant changes in purchasing in the desired direction for ≥1 of the foods targeted by the intervention, whereas education-only interventions in real stores were not.
Findings suggest that interventions implemented in grocery stores—particularly ones that manipulate price, suggest swaps, and perhaps manipulate item availability—have an impact on purchasing and could play a role in public health strategies to improve health. Review protocol registered at https://www.crd.york.ac.uk/PROSPERO/ as CRD42017068809.
Food purchasing is a key antecedent of food consumption, and interventions in grocery stores are of interest to those trying to change food purchasing to promote health and those concerned with the marketing and sales of foods and drinks (1). The goals of each may differ but the types of interventions are similar. These include economic interventions, such as financial incentives and/or disincentives (2), environmental interventions, which could work at the conscious or unconscious level (3), and education, or combinations of the above. Evaluating the effectiveness of these interventions is complex. Testing such interventions in real grocery stores is not always feasible, and thus some of the aforementioned strategies have been evaluated within simulated (e.g., virtual) stores, with potential for different effects. In addition, interventions to change food purchasing may attenuate or exacerbate health disparities. Socioeconomically disadvantaged populations are more likely to suffer from nutrition-related morbidity, and there is some evidence to suggest that certain interventions, particularly those relying on executive functioning, may be more effective in more socioeconomically advantaged groups (4–7). On the other hand, disadvantaged groups may be more sensitive to economic interventions (8).
A protocol was published in advance and is available in PROSPERO (https://www.crd.york.ac.uk/PROSPERO/; CRD42017068809) (12). Methods for searching, screening, data extraction, and quality assessment followed those set out in the Cochrane handbook (13).
This review includes 35 studies and, to the best of our knowledge, is the first to synthesize evidence from RCTs in grocery stores across a wide range of intervention types. The vast majority of studies (29 out of 35) aimed to improve health and we interpret the remainder in the context of their lessons for public health strategies. Overall, economic interventions showed the most promise, with 8 of the 9 studies in real store environments and all 6 studies in simulated environments detecting a statistically significant effect. The effects of these interventions appeared to be enhanced by additional promotional activity. Swap interventions appeared promising in real grocery stores, but only 2 studies tested them in this context. Interventions that altered the store environment showed mixed effects. In interventions that consisted solely of consumer education, findings were positive in simulated environments but for the most part no effect was detected in real grocery stores. The very limited data available suggested that the effects of economic interventions did not differ by SES, whereas studies of other in-store interventions presented evidence of both positive and negative impacts.